On Wed, Jan 22, 2014 at 10:48:08AM +0800, Jianguo Wu wrote:
> Hi Greg,
>
> Please queue this for 3.4 stable kernel. I adjust context and can be applied
> to 3.4 stable clean.
>
> ---
> From: Jianguo Wu <[email protected]>
> Date: Wed, 18 Dec 2013 17:08:54 -0800
> Subject: [PATCH] mm/memory-failure.c: recheck PageHuge() after hugetlb page
> migrate successfully
>
> commit a49ecbcd7b0d5a1cda7d60e03df402dd0ef76ac8 upstream.
>
> After a successful hugetlb page migration by soft offline, the source
> page will either be freed into hugepage_freelists or buddy(over-commit
> page). If page is in buddy, page_hstate(page) will be NULL. It will
> hit a NULL pointer dereference in dequeue_hwpoisoned_huge_page().
>
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000058
> IP: [<ffffffff81163761>] dequeue_hwpoisoned_huge_page+0x131/0x1d0
> PGD c23762067 PUD c24be2067 PMD 0
> Oops: 0000 [#1] SMP
>
> So check PageHuge(page) after call migrate_pages() successfully.
>
> Signed-off-by: Jianguo Wu <[email protected]>
> Tested-by: Naoya Horiguchi <[email protected]>
> Reviewed-by: Naoya Horiguchi <[email protected]>
> Cc: <[email protected]>
> Signed-off-by: Andrew Morton <[email protected]>
> Signed-off-by: Linus Torvalds <[email protected]>
> [wujg: backport to 3.4:
> - adjust context
> - s/num_poisoned_pages/mce_bad_pages/]
I am queuing your 3.4 backport to the 3.5 kernel as well. Thanks Jianguo.
Cheers,
--
Luis
> ---
> mm/memory-failure.c | 16 ++++++++++++----
> 1 files changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index d86fb20..7e95698 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1447,10 +1447,18 @@ static int soft_offline_huge_page(struct page *page,
> int flags)
> return ret;
> }
> done:
> - if (!PageHWPoison(hpage))
> - atomic_long_add(1 << compound_trans_order(hpage),
> &mce_bad_pages);
> - set_page_hwpoison_huge_page(hpage);
> - dequeue_hwpoisoned_huge_page(hpage);
> + /* overcommit hugetlb page will be freed to buddy */
> + if (PageHuge(hpage)) {
> + if (!PageHWPoison(hpage))
> + atomic_long_add(1 << compound_trans_order(hpage),
> + &mce_bad_pages);
> + set_page_hwpoison_huge_page(hpage);
> + dequeue_hwpoisoned_huge_page(hpage);
> + } else {
> + SetPageHWPoison(page);
> + atomic_long_inc(&mce_bad_pages);
> + }
> +
> /* keep elevated page count for bad page */
> return ret;
> }
> -- 1.7.7
>
>
> --
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